The investigators will combine experimental studies with computational simulations to uncover the neural underpinnings of taste processing. In so doing, they will provide insight into more general facets of sensory processing, such as the cause and effect of trial-to-trial variability, the role of attentiveness on cortical activity and the mechanisms of conditioning whereby a previously palatable substance is rendered unpalatable following a single association with nausea. These studies will use simulations to assess how variability at one scale can either enhance or reduce variability at a larger scale during normal cortical functioning. The studies will also use models and simulations, to uncover what changes in connections or cellular properties in a network of neurons lead to the altered behavioral response to a sensory stimulus seen in taste learning. Taste is an important, though underutilized, modality for addressing issues of sensory processing, since it has a strong connection to behavior and survival and can produce strong, rapid yet long-lasting learning. Moreover, recently the investigators have uncovered correlated changes of neural activity with the state of attentiveness of an animal during taste processing. The investigators will test how these attention-dependent changes of neural activity arise and will use simulations to assess the possible functional role of such changes. A transformative role of the research will be to change the way the apparent randomness of trial-to-trial variability is viewed. Rather than being a nuisance in the observation of neural data, the authors aim to show that such variability is an aspect of neural activity that can both provide information about underlying activity and be beneficial for some aspects of neural processing. An understanding of the modulation of noise, variability and oscillations with attentiveness will be beneficial for addressing deficiencies in all areas of sensory processing. More specifically, these investigations of what brain processes are involved in making one tastant highly desirable and another noxious may have far-flung clinical implications for, for instance, the treatment of some forms of obesity and the alleviation of childhood taste disorders caused by chemotherapy. Furthermore, an improvement in our understanding of normal cortical activity and its modulation by attention (via neuromodulators or by executive areas of the brain) will help us better address problems of abnormal cortical activity such as epilepsy and disorders of executive control associated with schizophrenia.